In-Line Water Hammer Arrester

ABSTRACT

An in-line water hammer arrester comprises a housing connectable at each end to a piping system, a fluid channel disposed within the housing to permit fluid to flow from the piping system through the housing and back into the piping system, a piston and a pressurized chamber. When a pressure spike occurs, the piston is pushed against the pressurized chamber allowing an expanded area for water flow until the pressure spike is dissipated and the piston returns to its resting position. When used with flexible hoses and tubing typically found with household appliance water supply lines, the in-line arrester is easily installed by a crimping or clamping type connector and takes up little space.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 14/109,116filed on Dec. 17, 2013, which is a continuation-in-part of U.S.application Ser. No. 13/837,256 filed on Mar. 15, 2013 (now U.S. Pat.No. 8,939,177).

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an in-line device for dampening pressurespikes and reducing “water hammer” caused by abrupt pressure changeswithin a pipe, hose, or flexible tubing when the flow of water (or otherfluid flowing through the system) is shut-off.

2. Description of Related Art

Water hammer is a common occurrence when there is a sudden change inpressure in a pipe caused by shutting-off the flow of water through thepipe. Pressure spikes associated with quick shut-off valves can be 5times or more greater than the normal pressure within the system. Thesechanges in pressure may cause rattling and shaking of the pipes,producing the typical “hammering” noise associated with this problem,although the pressure change may cause damage to the piping system evenwhen there is no hammering noise. The pressure spike can reverberatebackward from a valve and cause damage to parts throughout the system,including fittings, valves, backflow preventers, and appliancesconnected to the piping system.

One way of preventing water hammer is by installing a water hammerarrester. These devices typically include a pipe, capped at one end,with a piston and a pressurized air pocket between the piston and thecapped end, with the open end of the pipe connected to a pipe in thesystem just upstream of where a pressure spike may occur or connected ata valve and typically included in a valve outlet box. The arrester istypically installed perpendicular to the system pipe. When a pressurespike occurs, the pressurized water pushes against the piston in thearrester, which moves against the compressed air pocket until thepressure is stabilized and the piston returns to its normal, restingposition within the arrester. This dampens the pressure so that it doesnot reverberate back through the piping system.

This type of prior art hammer arrester works well with fixed pipinginstallations, but requires extra room for installation and larger sizedoutlet boxes to accommodate the arrester. Additionally, it is moredifficult to install since it typically involves soldering pipe,compression joints, crimping on to PEX, or other various means ofconnections. If it becomes necessary to retro-fit a piping system with ahammer arrester, then the difficulty increases since it is moredifficult to access piping within walls or to add a hammer arrestor atan existing outlet box. This usually requires the assistance of aprofessional plumber and is not usually a do-it-yourself job for theaverage homeowner. Moreover, this type of design does not work withflexible hoses and tubing typically found on washing machines,dishwashers, and refrigerators/ice makers, even though the valves usedwith these appliances may cause severe pressure spikes.

In-line type arresters are also known, which have advantages over aT-connector style arrester, but these use dampening materials ratherthan pistons. For example, U.S. Pat. No. 6,672,337 discloses acushioning diaphragm around a fluid chamber and U.S. Pat. No. 8,307,855discloses a set of gas-filled balloons within a larger diameter pipe fordampening the pressure spike. A piston is more effective than cushioningmaterials.

SUMMARY OF THE INVENTION

The water hammer arrester apparatus disclosed herein may be added tostandard and preexisting flexible hoses and tubing typically found onsupply lines for washing machines, dishwashers, and refrigerators/icemakers. According to one embodiment of the invention, the water hammerarrester is installed in-line in a flexible hose by crimping orotherwise sealing the water hammer arrestor in the middle of a standardhose. This way a water hammer arrestor installation is as easy for theaverage homeowner as installing a standard hose and it can be donewithout requiring professional assistance. Moreover, the apparatus isrelatively small and the diameter is only slightly larger than thetypical diameter of flexible hose supply lines for household appliances,so it can easily fit in the same space that housed a standard flexiblesupply line before installation of the arrester with supply line. Withthe use of the apparatus according to an embodiment of the invention, itwould not be necessary to install arresters in a valve outlet box, whichwill allow for smaller boxes which are less expensive.

According to another embodiment of the invention, the water hammerarrestor comprises a piston and a pressurized chamber, similar to priorart devices, but the arrestor is in-line with the system and the waterpasses through the arrester. This in-line design allows the arrester tobe compact and easy to install on existing flexible hoses or tubing.

These and other features, objects and advantages of the presentinvention will become better understood from a consideration of thefollowing detailed description of the preferred embodiments and appendedclaims in conjunction with the drawings. Although the discussion of thepreferred embodiment will focus on use of the apparatus with flexiblehoses and tubing, the invention may be used with copper pipe, CPVC pipe,PEX pipe, and other hard surface piping systems with different means ofconnecting the ends of the apparatus in-line with these pipes, as willbe understood by those of ordinary skill in the art. Additionally, theinvention may be installed inside an appliance, such as a washingmachine or dishwasher, by the manufacturer of the appliance, as willalso be understood by those of ordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

The apparatus of the invention is further described and explained inrelation to the following drawings wherein:

FIG. 1 is a cross-sectional view of a typical prior art T-connectorwater hammer arrester;

FIG. 2 is a perspective view of one embodiment of an apparatus accordingto the invention;

FIG. 3 is cross-sectional side elevation view of the apparatus of FIG. 2with the piston in its resting position;

FIG. 4 is a cross-sectional side elevation view of the apparatus of FIG.2 with the piston in fully compressed position;

FIG. 5 is cross-sectional side elevation view of the apparatus of FIG. 2as connected to a flexible hose;

FIG. 6 is a perspective view of another embodiment of an apparatusaccording to the invention;

FIG. 7 is a cross-sectional side elevation view of the apparatus of FIG.6 with the piston in its resting position;

FIG. 8 is a perspective view of another embodiment of an apparatusaccording to the invention;

FIG. 9 is a cross-section side elevation view of the apparatus of FIG.8;

FIG. 10 is a side elevation view of another embodiment of an apparatusaccording to the invention;

FIG. 11A is a cross-sectional side elevation view of the apparatus ofFIG. 10 with the piston in its resting position;

FIG. 11B is an enlarged view of a portion of FIG. 11A;

FIG. 12 is a perspective view of another embodiment of an apparatusaccording to the invention;

FIG. 13 is cross-sectional side elevation view of the apparatus of FIG.12 with the piston in its resting position;

FIG. 14 is a cross-sectional side elevation view of the apparatus ofFIG. 12 with the piston in fully compressed position;

FIG. 15 is a perspective view of one embodiment of an end fittingaccording to the invention;

FIG. 16A is a cross-sectional side elevation view of the end fitting ofFIG. 15;

FIG. 16B is an enlarged view of a portion of the end fitting of FIG.16A;

FIG. 17 is a perspective view of one embodiment of another end fittingaccording the invention;

FIG. 18A is a side elevation view of the end fitting of FIG. 17;

FIG. 18B is an enlarged view of a portion of the end fitting of FIG.18A;

FIG. 19 is a perspective view of one embodiment of a piston according tothe invention;

FIG. 20 is a side elevation view of the piston of FIG. 19;

FIG. 21 is a cross-sectional view of the piston of FIG. 20.

FIG. 22 is a perspective view of another embodiment of an apparatusaccording to the invention;

FIG. 23 is cross-sectional side elevation view of the apparatus of FIG.22 with the piston in its resting position;

FIG. 24 is a perspective view of another embodiment of an apparatusaccording to the invention;

FIG. 25 is cross-sectional side elevation view of the apparatus of FIG.24 with the piston in its resting position;

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a typical prior art hammer arrester 1 is shown.Arrester 1 comprises an end fitting 2, generally u-shaped housing 3, anda piston 4. End fitting 2 is attached, usually by a threaded or solderedconnection, to a tee 7 extending perpendicularly from a pipe 8. A fluidchamber 5 is disposed within end fitting 2. A pressurized chamber 6,usually filled with air, is disposed inside housing 3. When a pressurespike occurs, the force of fluid or water flowing through T-connector 7and through end fitting 2 causes piston 4 to move toward the sealed endof housing 3 as fluid chamber 5 expands to accommodate the additionalfluid from pipe 8. When the pressure normalizes, piston 4 moves back toits resting position (as shown in FIG. 1). The fluid or water in thesystem does not flow through (from one end and out through the otherend) arrester 1, but flows into and back out of the same opening in endfitting 2. When installed in a typical orientation, the longitudinalaxis of arrester 1 is perpendicular to the longitudinal axis of pipe 8and perpendicular to the primary flow direction of fluid or waterthrough the system. Adding arrester 1 to an existing piping systemusually requires cutting the pipe or hose, installing T-connector 7, andconnecting arrester 1. Depending on the materials used, this may requirethe use of harmful and malodorous solvents or the use of solder and atorch, making installation much more difficult for the average homeownerto handle without assistance from a professional plumber.

Referring to FIG. 2, one preferred embodiment of an in-line waterarrester apparatus 10 is depicted. Apparatus 10 preferably comprises asubstantially cylindrical outer housing or body 12 having a shoulder 52at each end, a first end fitting 22, a second end fitting 30, and alongitudinal fluid channel 34. During normal operation of a pipingsystem (including a system using hard pipe material or flexible hoses ortubing), fluid (usually water) flows from first fitting 22 (the upstreamor rearward end) toward the second fitting 30 (the downstream or frontend). Apparatus 10 is installed upstream from a valve that would closeand create a pressure spike. Typically, such a valve is part of theappliance with which the arrester is being used. For use with a washingmachine, for example, arrester 10 would be installed in the flexiblewater supply line between the water supply valve (which is usually leftin the on position and is not the source of the pressure spike)installed in the outlet box at the wall and the washing machine. Eachend fitting 22 and 30 preferably comprises a barbed end 24 and 32 and aneck portion 21 and 31 that extends outwardly beyond shoulder 52.Alternatively, arrester 10 may be installed inside an appliance, mostpreferably by the manufacturer of the appliance, near the appliancevalve that may cause water hammer.

A preferred embodiment of arrester apparatus 10 is depicted in FIGS. 3and 4. Arrester apparatus 10 comprises outer housing or body 12, firstend fitting 22, second end fitting 30, piston 14, pressurized chamber20, and fluid channels 34, 28, and 26. First end fitting 22 is disposedat the upstream end of housing 12. First end fitting 22 comprises acylindrical body 16 having an interior (or downstream) end 40 and ashoulder 41, a cylindrical neck 21 extending outwardly from shoulder 41,and barbed end 24. Shoulder 41 abuts shoulder 52 of housing 12. Neck 21extends outwardly (upstream) from housing 12 through aperture 54. Barbedend 24 is preferably widest near neck 21 and tapers as it extendsoutwardly from neck 21 to facilitate insertion into a flexible hose,with the widest, barbed portion helping to secure the barbed end 24 fromdislodging from the flexible hose. A longitudinal fluid channel 26extends through barbed end 24 and neck 21. Another fluid channel 28 isformed on the interior of cylindrical body 16. Fluid channel 28 has alarger diameter than fluid channel 26. Fluid, typically water flowingthrough the piping system, may freely flow from fluid channel 26 tofluid channel 28 when water is flowing through the system. At least one,and preferably at least two, annular recesses 35 are disposed within anexterior surface of a sidewall of body 16. Disposed within each annularrecess 35 is a sealing ring 36, which frictionally engages an interiorwall of housing 12 to secure first end fitting 22 within housing 12 andprevent water from leaking between housing 12 and first end fitting 22.

Second end fitting 30 is disposed at the downstream end of outer housingor body 12. Second end fitting 30 comprises a substantially cylindricalbody 18 having an interior (or upstream) end 46 and a shoulder 44, acylindrical fluid shaft 62, a cylindrical neck 31 extending outwardlyfrom shoulder 44, and barbed end 32. At least one, and preferably atleast two, annular recesses 35 are disposed within an exterior surfaceof a sidewall of body 18 that is adjacent an interior wall of housing12. Disposed within each annular recess 35 is a sealing ring 36, whichfrictionally engages an interior wall of cylindrical housing 12 tosecure second end fitting 30 within housing 12 and prevent material fromleaking out of pressurized chamber 20 between housing 12 and second endfitting 30. Shoulder 44 abuts shoulder 52 of cylindrical housing 12.Neck 31 extends outwardly (downstream) from housing 12 through aperture54. Barbed end 32 is preferably widest near neck 31 and tapers as itextends outwardly from neck 31 to facilitate insertion into a flexiblehose, with the widest, barbed portion helping to secure the barbed end32 from dislodging from the flexible hose.

Fluid shaft 62 extends inwardly (upstream) from neck 31. An upstream end45 of fluid shaft 62 extends partially into fluid chamber 28. An annularchamber 48 is formed between body 18 and fluid shaft 62. Chamber 48helps facilitate molding of body 18. Circumferentially spaced holes mayalso be partially disposed in body 18 to facilitate molding. Alongitudinal fluid channel 34 extends through barbed end 32, neck 31,and fluid shaft 62. Fluid channels 26, 28, and 34 cooperate to provide acontinuous fluid channel through arrester apparatus 10. Pressurizedchamber 20 is formed between an interior wall of housing 12, an exteriorwall of fluid shaft 62, end 43 of piston 14, and end 46 of body 18. Thetotal assembly should meet the latest edition of ASSE 1010 testingstandards to adequately reduce the impact of a pressure spike in thesystem. Although air is the preferred gas to use in pressurized chamber20, other gases, preferably inert gases such as nitrogen, may also beused. Other materials, such as water or gel, foam, or mechanicalstructures (such as springs) may also be used with pressurized chamber20.

Apparatus 10 is preferably assembled by placing piston 14 over shaft 62,inserting end fittings 22 and 30 inside housing 12, hermetically sealingand pressurizing chamber 20 (preferably to 35-45 psi), and otherwisesealing end fittings 22 and 30 to housing 12. Preferably, housing 12 isinitially a cylindrical piece of pipe that can be swaged to formshoulders 52 at each end over the shoulders 41 and 44 of the endfittings 22 and 30. Once shoulders 52 are formed, the fluid pressurewithin the apparatus holds the end fittings 22 and 30 in place againsthousing 12.

A preferred embodiment of water hammer arrester apparatus 10, asinstalled on a flexible hose, is depicted in FIG. 5. Flexible hose 68connected to a water supply line and an appliance, for example, is cutto expose two open ends. A clamp or crimp-type connector 70 is insertedover each of barbed ends 24 and 32 and abuts a recessed area on shoulder52 of housing 12 (the recessed area best viewed in FIG. 1). Connector 70preferably has a hose end 76, a neck 72, and a shoulder end 74. A cutend of hose 68 is inserted into hose end 76 of connector 70 and barbedend 24 is inserted into the cut end of hose 68 inside connector 70. Theother cut end of hose 68 is similarly inserted into hose end 76 of thesecond connector 70 and barbed end 32 is inserted into the cut end ofhose 68 inside the second connector 70. Each connector 70 is thencrimped or clamped to secure hose 68 to arrester apparatus 10. Any othertype of connector suitable for use with flexible hoses or tubing, may beused to connect hose 68 to arrester apparatus 10. Arrester apparatus 10may be preassembled with shoulder end 74 of connector 70 attached atboth ends of apparatus 10, two connectors 70 may come pre-packaged withapparatus 10, or connectors may be purchased separately from apparatus10. Arrester apparatus 10 may also be used with copper pipe, CPVC, PEXor other hard piping systems using suitable connectors to connect thearrester to the piping as will be understood by those of ordinary skillin the art. Although not shown in the drawings, the ends of hoses 60 and68 preferably abut shoulder 74.

Alternatively, arrester 10 may include threaded or crimping or clampingtype connectors pre-attached to or integrally manufactured with eitherend fittings 22 and 30 and/or housing 12. Such connectors may includewashers or similar fittings to prevent water leakage. Such connectorswould mate with similar connectors installed on a flexible hose ortubing or piping with which arrester 10 is to be used. In this alternateconfiguration, barbed ends 24 and 32 may not be necessary and it may notbe necessary for necks 21 and 31 to extend outwardly from housing 12. Asyet another alternative, arrester 10 may be integrated with orpre-attached to a flexible hose, tubing, or a length of pipe for easierinstallation. For example, the ends of a flexible hose may come withthreaded connectors that are ready to attach to the water supply valveand the inlet of a washing machine, with the arrester 10 already inplace on the flexible hose so the user need only tighten the connectionsat the valve and washer inlet, rather than cutting the hose and havingto install the arrester with crimp connectors. Those of ordinary skillin the art will understand the modifications that would be needed forsuch alternate connection configurations.

First end fitting 22, second end fitting 30, and piston 14 are eachpreferably unitarily molded as a single part. The preferred materialsfor first end fitting 22, second end fitting 30, and piston 14 areAcetal, but other plastic or metal materials, such as polysulfone,polyphynelsulfone, steel, brass, or other copper alloy, may also beused. Sealing rings 36, 38, and 60 are preferably standard o-rings. Mostpreferably, sealing rings 38 are smaller in size than sealing rings 36and 60, which may be the same size. Additionally, annular recesses 35 onthe first end fitting and the second end fitting may be the same size ordifferent sizes, with the sealing rings 36 sized accordingly. Housing 12is most preferably made of stainless steel, but other materials, such ascopper or aluminum or other metals or plastics may also be used.

Referring to FIGS. 6-7, another preferred embodiment of an in-line waterarrester apparatus 110 is depicted. Apparatus 110 preferably comprises asubstantially cylindrical outer housing or body 112, a substantiallycylindrical interior housing or body 113, a first end fitting 122, asecond end fitting 130, and a piston 14. A crimp portion 178 is disposedat each end of outer housing or body 112. First end fitting 122 isdisposed at the upstream end of housing 112 and comprises asubstantially cylindrical body 116, an annular shoulder 141, asubstantially cylindrical neck 121 extending outwardly from shoulder141, and barbed end 124. An upstream end of housing 112 abuts shoulder141. Preferably, shoulder 141 has an outwardly protruding lip 145 andcylindrical body has an outwardly protruding lip 117. Housing 112 ispreferably crimped between lips 145 and 117, forming crimped portion178, to secure first end fitting 122 within housing. A longitudinalfluid channel 126 extends through barbed end 124 and neck 121. Anotherfluid channel 128 is formed on the interior of cylindrical body 116.

Second end fitting 130 is disposed at the downstream end of housing 112.Second end fitting 130 comprises a substantially cylindrical body 118,an annular shoulder 144, a substantially cylindrical fluid shaft 162extending inwardly (upstream) from body 118, a substantially cylindricalneck 131 extending outwardly from shoulder 144, and a barbed end 132. Adownstream end of housing 112 abuts shoulder 144. Preferably, shoulder144 has an outwardly protruding lip 147 and body 118 has an outwardlyprotruding lip 119. Housing 112 is preferably crimped between lips 119and 147, forming crimped portion 179, to secure second end fitting 130within housing. An upstream end of fluid shaft 162 extends partiallyinto fluid chamber 128. One or more holes 148 may be provided in body118 to facilitate molding. A longitudinal fluid channel 134 extendsthrough barbed end 132, neck 131, body 118, and fluid shaft 162. Fluidchannels 126, 128, and 134 cooperate to provide a continuous fluidchannel through arrester apparatus 110. Pressurized chamber 120 isformed between an interior wall of housing 113, an exterior wall offluid shaft 162, the downstream end of piston 114, and the upstream endof body 118.

At least one, and preferably at least two, annular recesses 135 aredisposed within an exterior surface of a sidewall of body 118 and ofbody 116. Disposed within each annular recess 135 is a sealing ring 136,which frictionally engages an interior wall of crimp portions 178 and179 and/or an interior wall of housing 113 to secure second end fitting130 and first end fitting 122 within housing 112 and housing 113. Asingle recess 135 and a single sealing ring 136 may be also be used oneither or both body 118 and 116 (as in FIG. 9A). If only a singlesealing ring 136 is used, it is preferred that it be disposed in theinterior most recess 135, to frictionally engage an interior of housing113. Sealing rings 136 prevent leakage between end fittings 122 and 130and housing 112 and housing 113.

First end fitting 122, second end fitting 130, and interior housing 113are each preferably unitarily molded as separate, single parts fromplastic materials. Housing 112 is preferably stainless steel, but othermetals such as copper or aluminum, and plastics may also be used. Whenassembled, crimp portions 178 and 179 are crimped to secure the endfittings 122 and 130 together with housing 112, with housing 113disposed inside housing 112 and between lips 117 and 119 of the endfittings. Other methods of connection suitable for the materials fromwhich these parts are manufactured may also be used.

Apparatus 110 is preferably assembled by placing piston 14 over shaft162, inserting interior housing 113 in housing 112, inserting endfittings 122 and 130 inside housing 112 and 113, hermetically sealingand pressurizing chamber 120 (preferably to 35-45 psi), and crimpinghousing 112 at crimp portions 178 and 179 to secure the end fittings122, 130 inside housing 112.

Referring to FIGS. 8-9, another preferred embodiment of an in-line waterarrester apparatus 210 is depicted. Apparatus 210 preferably comprises afirst end fitting 222, a second end fitting 230, and a piston 14. Endfitting 230 is preferably a tube made of copper or copper alloy that isswaged into shape. First end fitting 222 is also preferably a tube madeof copper or a copper alloy and is swaged into shape and joined with endfitting 230 at shoulders 252 and 244. Although copper or copper alloysare preferred, other materials may be used and other methods of joiningthe two fittings suitable for the particular materials may be used.

First end fitting 222 is disposed at the upstream end of arrester 210.First end fitting preferably comprises a cylindrical body 212, annularshoulder 241, a barbed end 224, and a neck portion 221 extendingoutwardly (upstream) from annular shoulder 241. Barbed end 224 isdisposed at the upstream end of neck 221. A longitudinal fluid channel226 extends through barbed end 224 and neck 221.

Second end fitting 230 is disposed at the downstream end of arrester210. Second end fitting 230 preferably comprises annular shoulder 244, aneck portion 231 extending outwardly (downstream) from shoulder 244, abarbed end 234 extending outwardly from neck 231, a substantiallycylindrical body 218, and a cylindrical fluid shaft 262 extendinginwardly (upstream) from body 218. Preferably, shoulder 244 has anoutwardly protruding lip 247. An annular recess 235 is disposed withinan exterior surface of a sidewall of body 218 and a sealing ring 236 isdisposed within recess 235. The downstream end of body 218 comprises ashoulder around which cylindrical body 212 is swagged. Recess 237 isdisposed between the downstream shoulder of body 218 and shoulder 244.End fitting 230 is preferably made of brass, but other materials mayalso be used. The downstream end 252 of body 212, which is preferablymade of copper or a copper alloy, is preferably swaged between thedownstream shoulder of body 218 and lip 247 to secure second end fitting230 to first end fitting 222.

Apparatus 210 is preferably assembled by placing piston 14 over shaft262, inserting end fitting 230 into body 212 of end fitting 222,hermetically sealing and pressurizing chamber 220 (preferably to 35-45psi), and swaging together at shoulders 252 and 244 (or otherwisesealing end fittings 222 and 230 together, depending on the materialsused).

Referring to FIGS. 10-11B, another preferred embodiment of an in-linewater arrester apparatus 310 is depicted. Apparatus 310 preferablycomprises an outer housing or body 312, interior fitting 340, and piston14. Interior fitting 340 preferably comprises a substantiallycylindrical body 318 and a substantially cylindrical fluid shaft 362extending upstream from body 318. A fluid channel 334 is disposedthrough the interior of shaft 362 and body 318. At least one annularrecess 335 is disposed within an exterior surface of a sidewall of body318 that is adjacent an interior wall of housing 312, as best seen inFIG. 11B. Disposed within each annular recess 335 is a sealing ring 336,which frictionally engages an interior wall of cylindrical housing 312.Pressurized chamber 320 is formed between an interior wall of housing312, an exterior wall of fluid shaft 362, the downstream end of piston14, and an upstream end of body 318. Sealing ring 336 also preventsmaterial from leaking out of pressurized chamber 320 between housing 312and interior fitting 340. Interior fitting 340 is preferably made ofbrass, but other materials may also be used.

Housing 312 is initially cylindrical in shape and preferably made ofcopper, but other materials may also be used. Interior fitting 340 isplaced inside housing 312 and then the downstream end of housing 312(nearest body 318) is swaged into shape to form an end fitting 330. Endfitting 330 preferably comprises a shoulder 352, neck 331, and barbedend 332, with fluid channel 380 being disposed within end fitting 330.An annular inwardly projecting lip 333 is also formed in housing 312near shoulder 352. Lip 333 prevents body 318 of interior fitting 340from further movement in the downstream direction. Chamber 320 is formedon the exterior of shaft 362 and interior of housing 312. Chamber 320 ispressurized, piston 14 is inserted over shaft 362 to seal pressurizedchamber 320, and the upstream end of housing 312 is swaged into shape toform an end fitting 320. End fitting 320 preferably comprises a shoulder341, neck 321, and barbed end 321, with fluid channel 326 being disposedwithin end fitting 322. Fluid channels 326, 334, and 380 cooperate toprovide a continuous fluid channel through arrester apparatus 310. Anannular inwardly projecting lip 323 is also formed in housing 312 nearshoulder 341. Lip 323 prevents piston. 14 from further movement in theupstream direction. Most preferably, housing 312 retains a cylindricalshape between formed end fittings 322 and 330. Housing 312, interiorfitting 340 and piston 14 are preferably separate components, but otherconfigurations, such as separate end fittings 322 and 330 or interiorfitting 340 being unitarily molded with end fitting 330 as a separatecomponent, may also be used. The methods of joining these componentstogether will vary according to the materials used and theconfigurations of the components as will be understood by those ofordinary skill in the art.

Piston 14 in arrester embodiments 10, 110, 210, and 310 is essentiallythe same piston, although different sizes and materials may be usedaccording to each embodiment. Piston 14 is preferably substantiallycylindrical and unitarily molded from plastic materials, but othermaterials and metals may be used. To facilitate molding, piston 14 mayinclude an annular recess, such as recess 17 depicted in FIG. 5, orcircumferentially spaced holes disposed partially through the body ofthe piston, as will be understood by those of ordinary skill in the art.At least one, and preferably at least two, annular recesses 56 aredisposed within an exterior surface of a sidewall of piston 14.Additionally, at least one, and preferably at least two, annularrecesses 58 are disposed within an interior surface of a sidewall ofpiston 14. Disposed within each annular recess 56 is a sealing ring 60,which provides slidable engagement between piston 14 and an interiorwall of housing/body 12, 113, 212, or 312. Disposed within each annularrecess 58 is another sealing ring 38, which provides slidable engagementbetween piston 14 and an exterior wall of fluid shaft 62, 162, 262, or362. Alternatively, outwardly or inwardly protruding retaining members(similar to those depicted in FIG. 23 discussed below) or integral lips(similar to those depicted in FIGS. 13 and 19 discussed below) may beused instead of annular recesses 56 and 58. Similar retaining members orintegral protruding lips may also be used in place of sealing rings forother parts of arresters according to the invention, such as to replacesealing ring 236. Sealing rings 60 and 38 prevent leakage between thevarious upstream fluid channels (e.g. 28) and pressurized chamber 20,120, 220, or 320.

Under normal operating conditions, when the pressure in the pipingsystem is stable, piston 14 is in its resting position as shown in FIGS.3, 5, 7, 9A, 9C, and 11A. When at rest, the pressure in pressurizedchamber 20, 120, 220, or 320 is greater than the pressure in the fluidsystem (e.g. the pressure in the upstream fluid channel nearest piston14, such as fluid channel 28). At least a portion of the upstream end ofpiston 14 abuts another part of the arrester to prevent further rearwardmovement of piston 14 when the pressure in the pressurized chamber isgreater than the pressure in the system, thus holding piston 14 in aresting position. In embodiments 10 and 110, part of end 42 of piston 14abuts end 40 of body 16 or end 140 of body 116 as shown in FIGS. 3, 5,and 7. In embodiment 210, as shown in FIGS. 9A-9C, an annular lip 223 orsimilar protrusion may be disposed at or near the upstream end of shaft262 to prevent piston 14 from rearward movement beyond lip 223.Alternatively, the upstream end of piston 14 may abut shoulder 241 withshaft 262 being longer than depicted in FIGS. 9A-9C so that piston 14remains at least partially on shaft 262 when in the resting position. Inembodiment 310, an inwardly projecting annular lip 323 prevents furtherrearward movement of piston 314 beyond the lip at the upstream end ofhousing 312. Alternatively, an upstream end of piston 14 may abutshoulder 341 in arrester 310. A lip or other protrusion to preventfurther rearward movement of piston 14 may be incorporated at or nearthe upstream end of shaft 62, 162, 262, or 362, or at the upstream endof housing 12, 113, 212, or 312 in any of these embodiments.

When a pressure spike occurs, the pressure in the system (e.g. thepressure in the upstream fluid channel nearest piston 14, such as fluidchannel 28) becomes greater than the pressure in pressurized chamber 20,120, 220, or 320, causing piston 14 to move forward toward second endfitting 30, 130, 230, or 330. Piston 14 may move forwardly as needed toaccommodate the pressure spike. For a severe spike, piston 14 may moveforwardly until its downstream end abuts or nearly abuts the second endfitting, subject to the compressibility limits of the material withinthe pressurized chamber. In embodiment 10, end 43 abuts end 46 of secondend fitting 30, as shown in FIG. 4 as chamber 48 may accommodate thematerial in chamber 20 when piston 14 is pushed all the way forward. Ifsimilar chambers or holes are not provided in the second end fittings,or such chambers or holes are not facing and open to the pressurizedchamber, then piston 14 will not fully abut the second end fitting.

When the piston 14 is pushed forward from its resting position, anexpanded fluid chamber, such as fluid chamber 29 as shown in FIG. 4, isformed. The expanded fluid chamber forms in an area inside housing/body12, 113, 212, or 312, allowing a greater volume for the fluid in thesystem to fill. The shock of the pressure spike is transferred throughthe piston to the material in the pressurized chamber 20, 120, 220, or320. As the pressure in the system stabilizes, piston 14 moves back toits resting position. This movement pushes fluid out of the expandedchamber and back into the upstream fluid channel nearest piston 14 (e.g.fluid channel 28) and then out through the other fluid channels withinthe arrester (e.g. channel 34) and allows re-expansion of a compressiblematerial in pressurized chamber 20, 120, 220, or 320.

Referring to FIGS. 12-14, another preferred embodiment of an in-linewater arrester apparatus 410 is depicted. Apparatus 410 preferablycomprises a first end fitting 422, a second end fitting 430, and apiston 414. Pressurized chamber 420 is formed between an interior wallof body 412, an exterior wall of fluid shaft 462, a downstream end ofpiston 414, and annular shoulder 444. Piston 414 is shown in its restingposition in FIG. 13, when no pressure spike is occurring and thepressure in pressurized chamber 420 is greater than the pressure in thesystem at fluid channel 428. One or more ribs 413 prevent piston 414from sliding off the end of shaft 462. Preferably there are three ribs413 spaced in substantially equidistant positions around the interior ofshoulder 441. Piston 414 is shown in its compressed position in FIG. 14,when a pressure spike is occurring and the pressure in the system atfluid channel 428 is greater than the pressure in pressurized chamber420. The position of piston 414 along shaft 462 between the resting andcompressed positions will depend on the severity of the pressure spikeand the compressibility of the material in the pressurized chamber. Fora severe spike, piston 414 may move forwardly until its downstream endnearly abuts shoulder 444 (subject to the compressibility limits of thematerial inside pressurized chamber 420), as shown in FIG. 14. Fluidchamber 428 is formed between shoulder 441, a sidewall of body 412, asidewall of fluid shaft 462, and the upstream end of piston 414. Whenpiston 114 is pushed forward from its resting position, fluid chamber128 expands as shown in FIG. 14, allowing a greater volume for the waterto fill. As the pressure in the system stabilizes, piston 414 moves backto its resting position, pushing fluid out of expanded fluid chamber 428and back into the resting volume of fluid channel 428 and channels 426and 434, and allowing any compressible material in pressurized chamber420 to expand back to its resting state. Fluid channels 426, 428, and434 cooperate to provide a continuous fluid channel through arresterapparatus 410.

Referring to FIGS. 13-16B, first end fitting 422 comprises asubstantially cylindrical outer housing or body 412, an annular shoulder441, a neck portion 421 extending outwardly (upstream) from annularshoulder 441, a barbed end 424 extending outwardly from neck 421, ribs423 disposed around neck 421, and fluid channels 426 and 428. Theexterior surface of body 412 preferably comprises ribs 415 in acircumferential and longitudinal direction. Ribs 415 are optional, butmay add strength to the body 412, particularly if it is made of plasticmaterials. A lip 440 and stepped shoulder 457 are disposed at thedownstream end of body 412 to facilitate joining first end fitting 422to second end fitting 430 at joint 463. Barbed end 424 is disposed atthe upstream end of neck 421. Ribs 423 are preferably included aroundneck 421 to further help secure barbed end 424 and neck 421 inside aflexible hose. Alternatively, threads may be provided around neck 421 tooptionally threadably engage corresponding threads on another fittingattached to the flexible hose to secure first end fitting 422 to thehose. A longitudinal fluid channel 426 extends through barbed end 424and neck 421. Another fluid channel 428 is formed on the interior ofhousing 412. Fluid may freely flow from fluid channel 426 to fluidchannel 428 when fluid is flowing through the system. First end fitting422 is preferably unitarily molded from plastic material, but othermaterials, including metals may be used. Most preferably, first endfitting 422 is molded from glass-filled acetal, POM (polyoxymethylene oracetal), or polyphenylsulfone.

Referring to FIGS. 13-14 and 17-18B, second end fitting 430 is disposedat the downstream end of arrester 410. Second end fitting 430 comprisesannular shoulder 444, a neck portion 431 extending outwardly(downstream) from shoulder 444, a barbed end 432 extending outwardlyfrom neck 431, ribs 433 disposed around neck 431, a substantiallycylindrical fluid shaft 462, an a fluid channel 434 disposed insideshaft 462 and through neck 431 and barbed end 432. Annular shoulder 444preferably has ribs 415 for added strength, but ribs 415 are optional.Ribs 433 are preferably included around neck 431 to further help securebarbed end 432 and neck 431 inside a flexible hose. Alternatively,threads may be provided around neck 431 to optionally threadably engagecorresponding threads on another fitting attached to the flexible hoseto secure second end fitting 430 to the hose. Fluid shaft 462 extendsinwardly (upstream) from shoulder 444. An upstream end of fluid shaft462 is substantially flush with the upstream end of piston 414 whenpiston 414 is in its resting position (as shown in FIG. 13). One or moreribs 413 prevent piston 414 from sliding off the upstream end of shaft462. Alternatively, an upstream end of shaft 462 may extend partiallyinto fluid chamber 428 with piston 414 being recessed from the upstreamend of fluid shaft 462. Second end fitting 430 is preferably unitarilymolded from plastic material, but other materials, including metals maybe used. Most preferably, second end fitting 430 is molded fromglass-filled acetal, POM (polyoxymethylene or acetal), orpolyphenylsulfone.

Referring to FIGS. 13, 16B and 18B, the downstream end of body 412comprises a protruding lip 440 and a stepped shoulder 457 that engagewith recess 451 on annular shoulder 444 of second end fitting 430 toform joint 463. End fitting 422 is preferably secured to end fitting 430at joint 463 by ultrasonic welding of these parts. Other configurationsfor joining the end fittings may be used, such as spin welding,adhesives, snap-fit configurations, or threadable engagement, as will beunderstood by those of ordinary skill in the art.

Referring to FIGS. 19-21, piston 414 is preferably substantiallycylindrical. Piston 414 preferably comprises an inner ring 482 and anouter ring 484. Outer ring 484 preferably comprises exterior surface 486and interior surface 488 forming annulus 480 through which shaft 462 isinserted. Annular lips 460 are formed at each end of exterior surface486. Similarly annular lips 438 are formed at each end of interiorsurface 488. Inner ring 482 is preferably made from plastic materials,but other materials, including metals, may be used. Most preferably,inner ring 482 is made from ABS (acrylonitrile butadiene styrene). Outerring 484 is preferably made from rubber or plastic materials, but othermaterials capable of sliding inside body 412 and along shaft 462 may beused. Most preferably, outer ring 484 is made from TPV material.Suitable materials for outer ring 484 include EPDM rubber (ethylenepropylene diene monomer) or NBR rubber (acrylonitrile-butadiene).Preferably, a portion of outer ring 484 is molded, inner ring 482 isinserted and then additional material is molded to outer ring 484 tohold inner ring 482 in place, in an overmolding process that is wellknown to those of ordinary skill in the art. A two shot process alongwith an overmolding process or the use of adhesives to combine the twoparts may also be used. Inner ring 482 may be fully encased within outerring 484 or part of inner ring 482 may be left exposed through opening490 in the overmolding process. As an alternative to lips 460 and 438,piston 414 may be made with recesses or protruding retaining members andsealing rings may be used, similar to piston 14.

Referring again to FIGS. 13-14, when arrester 410 is assembled, anannular recess 456 forms between an interior surface of body 412,exterior surface 486 of piston 414 and annular lips 460. A similarannular recess 458 is formed between an exterior surface of shaft 462,interior surface 488 of piston 414, and annular lips 438. Annular lips460 and 438 frictionally engage housing 412 and shaft 462, respectively,to prevent fluid from fluid channel 428 or material inside pressurizedchamber 420 (such as gas or water or gel) from leaking to or from fluidchannel 428 and pressurized chamber 420. Annular recesses 456 and 458reduce friction to allow piston 414 to slide more easily inside housing412 and along shaft 462; however, other configurations for piston 414may be used, including recesses with separate sealing rings as withpiston 14.

Apparatus 410 is assembled by placing piston 414 over shaft 462,inserting shaft 462 inside body 412, hermetically sealing andpressurizing chamber 420 (preferably to 35-45 psi), and welding orotherwise sealing end fittings 422 and 430 together.

Referring to FIGS. 22-23, another preferred embodiment of an in-linewater arrester apparatus 510 is depicted. Apparatus 510 preferablycomprises a first end fitting 522, a second end fitting 530, interiorhousing or body 512, and a piston 514. Piston 514 is again shown in itsresting position in FIG. 23. When a pressure spike occurs, piston 514moves from this position sliding along the interior of housing 512toward the downstream end of arrester 510 to transfer the shock of thepressure spike to the material within pressurized chamber 520.

First end fitting 522 is disposed at the upstream end of arrester 510and preferably comprises a substantially cylindrical body 533, annularshoulder 541, neck 521, and barbed end 524. Fluid channel 526 isdisposed within neck 521 and barbed end 524 of first end fitting 522.Another fluid channel 528 is disposed within body 533. In thisembodiment, neck 521 partially extends into the interior of body 533 toabut an upstream end 568 of interior housing 512 to prevent rearwardmovement of interior housing 512, with the upstream end 568 of housing512 and the extending part of neck 512 being configured to have anopening to allow fluid to flow from fluid channel 526 and into channel528 and reservoir 570.

Second end fitting 530 is disposed at the downstream end of arrester 510and preferably comprises substantially cylindrical body 562, annularshoulder 552, neck portion 531, and barbed end 532. One or more ribs 563are disposed on the interior surface of body 562 near neck 531. Ribs 563abut end 564 of interior housing 512 to prevent forward movement ofhousing 512 while still allowing fluid to flow from channel 582(disposed within body 562) to channel 534 (disposed within neck 531).Fluid channels 526, 528, 582, and 534 cooperate to provide a continuousfluid channel through arrester apparatus 510. Fluid may freely flowbetween these channels. When arrester 510 is assembled, interior housing512 is disposed partially within body 533 and partially within body 562.The upstream end of body 562 is disposed within cylindrical body 533.Alternatively, body 562 may be disposed around the exterior ofcylindrical body 533. End fittings 522 and 530 are preferably joinedtogether where body 562 and body 533 overlap using any type ofconnection suitable for the materials from which the fittings aremanufactured. End fitting 522 and end fitting 530 are each preferablyunitarily molded from plastics or metals.

Disposed between and on the interiors of end fittings 522 and 530 isinterior housing 512. Interior housing 512 preferably comprises asubstantially cylindrical body with an upstream end 568 and a sealeddownstream end 564. Aperture 566 is disposed through upstream end 568 toallow fluid flowing through fluid channel 526 to contact piston 514.Arms 535 extend rearwardly from upstream end 568 and are configured tobe inserted inside the portion of neck 521 that extends into body 533 tohold housing 512 in place within end fitting 522. Alternatively, arms535 could fit around the outside of the extending portion of neck 521.Housing 512 is preferably a separate component of arrester 510, but maybe integrally formed with or otherwise connected to either end fitting522 or 530 to hold housing 512 in position inside arrester 510 and allowfluid to freely flow from channel 526 to 528 (and on through other fluidchannels in arrester 510 as discussed below).

Piston 514 is disposed inside interior housing 512. Piston 514preferably comprises a substantially u-shaped body 572 and retainingmembers 574 protruding outwardly from body 572. At least one annularrecess 556 is formed by retaining members 574. Preferably there are atleast three retaining members 574 that form two recesses 556. Disposedwithin each annular recess 556 is a sealing ring 560, which providesslidable engagement between piston 514 and an interior wall of housing512. Sealing rings 560 prevent fluid/water in the system and materialinside pressurized chamber 520 (such as gas or water or gel) fromleaking to or from fluid chambers 526, 528, 582, or 534 and pressurizedchamber 520. Alternate configurations, such as recesses with sealingrings or protruding lips, similar to pistons 14 and 414, may also beused with piston 514. The upstream end of body 572 abuts an interiorsurface of end 568 of interior housing 512 so that the open end of body572 is substantially aligned with aperture 566. A fluid reservoir 570 isdisposed within an interior portion of body 572. Piston 514 ispreferably unitarily molded from plastics or metals.

Pressurized chamber 520 is formed between an interior side wall ofhousing 512, downstream end 564, a downstream surface of piston body572, and a downstream surface of a retaining member 574. Rearwardmovement of piston 514 is stopped by contact between an upstream end ofpiston body 572 and end 568 of housing 512. During normal fluid flowthrough the system, fluid fills reservoir 570 but the pressure is notgreat enough to cause piston 514 to move forwardly within interiorhousing 512. When a pressure spike occurs, the force of the fluid in thesystem against the interior of body 574 causes piston 514 to slideforwardly within interior housing 512, toward downstream end 564. Whenpiston 514 moves forwardly, fluid in the system is allowed to partiallyfill an interior reservoir within housing 512 on the upstream side ofreservoir 570. For a severe spike, piston 514 may move forwardly untildownstream end of piston 514 nearly abuts end 564. When the pressurenormalizes, fluid is pushed out of the expanded reservoir inside housing512 and back into fluid channel 528 (and on out of arrester 510 throughchannels 582 and 534) as piston 514 returns to its resting position.

Arrester 512 is preferably assembled by inserting piston 514 insidehousing 512, inserting housing 512 inside one of the end fittings,inserting end fitting 530 inside end fitting 522, hermetically sealingand pressurizing chamber 520, and sealing the end fittings where body533 and body 562 overlap, using any connection suitable for thematerials.

Referring to FIGS. 24-25, another preferred embodiment of an in-linewater arrester apparatus 610 is depicted. Apparatus 610 preferablycomprises a first end fitting 622, a second end fitting 630, and apiston 614. Piston 614 is again shown in its resting position in FIG.25. When a pressure spike occurs, piston 614 moves from this positionsliding along the interior of body 612 and the interior of shaft 662toward the downstream end of arrester 610 to transfer the shock of thepressure spike to the material in pressurized chamber 620.

First end fitting 622 is disposed at the upstream end of arrester 610and preferably comprises a substantially cylindrical body 633, annularshoulder 641, neck 621, and barbed end 624. Fluid channel 626 isdisposed within neck 621 and barbed end 624 of first end fitting 622.Second end fitting 630 preferably substantially forms the outer housingor body of arrester 610, comprising substantially cylindrical body 612and substantially cylindrical shaft 662. Second end fitting 630 alsopreferably comprises annular shoulder 688, annular shoulder 690, annularshoulder 644, neck portion 631, and barbed end 632. Fluid channel 682 isdisposed within shaft 662 and fluid channel 634 is disposed within neck631. Fluid may freely flow between channels 682 and 634.

Piston 614 preferably comprises a substantially cylindrical body 672,annular shoulder 643, and a substantially cylindrical shaft 674. Body672 is open on the upstream end and abuts shoulder 643 on the downstreamend. Fluid channel 670 is disposed within shaft 674 and through shoulder643. Cylindrical body 672 and annular shoulder 643 form a substantiallyu-shaped configuration, with fluid channel 628 disposed within aninterior of the u-shaped configuration. Fluid channels 626, 628, 670,682, and 634 cooperate to provide a continuous fluid channel througharrester apparatus 610. At least one annular recess 656 is disposedwithin an exterior surface of a sidewall of body 672 that is adjacent aninterior wall of body 612. Disposed within each annular recess 656 is asealing ring 660, which provides slidable engagement between piston 614and an interior wall of body 612. A downstream end shaft 674 is disposedwithin shaft 662. Another sealing ring 638 is disposed within recess 658near shoulder 690. Sealing ring 638 remains stationary, but allows shaft674 to slide relative to shaft 662. Alternatively, shaft 674 could havea sealing ring disposed around its exterior that slides within shaft 662and with shaft 674. Sealing rings 660 and 638 prevent water and materialinside pressurized chamber 620 (such as gas or water or gel) fromleaking to or from fluid chambers 626, 628, or 682 and pressurizedchamber 620.

Pressurized chamber 620 is formed between an interior side wall of body612, an upstream surface of shoulder 688, a downstream surface ofshoulder 643, and an exterior wall of fluid shaft 674. Rearward movementof piston 614 is stopped by contact between an upstream end of pistonbody 672 and the downstream surface of shoulder 641. When piston 614 isin its resting position (as shown in FIG. 25), the downstream end shaft674 is disposed within shaft 662. A pressure spike in the system causespiston 614 to move forward, toward shoulder 688, as needed toaccommodate the pressure spike. For a severe spike, piston 614 may moveforwardly until downstream end of shoulder 643 nearly abuts theupstream/interior surface of shoulder 688. As piston 614 moves forwardlyin response to a pressure spike, shaft 674 slides within shaft 662.Fluid chamber 628 expands within the interior of body 612 when piston614 is pushed forward from its resting position.

End fitting 622, end fitting 630, and piston 614 are each preferablyunitarily molded from plastics or metals. The upstream end of body 612is disposed within cylindrical body 633 and abuts thedownstream/interior surface of shoulder 641. Alternatively, body 612 maybe disposed around the exterior of cylindrical body 633. End fittings622 and 630 are preferably joined together where body 612 and body 633overlap using any type of connection suitable for the materials.

Arrester 610 is preferably assembled by inserting piston 614 inside endfitting 630, inserting end fitting 630 inside end fitting 622,hermetically sealing and pressurizing chamber 620, and sealing the endfittings where body 633 and body 612 overlap, using any connectionsuitable for the materials.

Pressure spikes in fluid or piping systems (including a system usinghard piping, flexible hoses or tubing, or combination) occur upstream ofa closing valve. Arresters according to the invention are installedupstream from a valve in a fluid or piping system that would close andcreate a pressure spike. Typically, such a valve is part of theappliance with which the arrester is being used. For use with a washingmachine, for example, arresters according to the invention would beinstalled in the flexible water supply line between the water supplyvalve installed in the outlet box at the wall (which is usually left inthe on position and is not the source of the pressure spike) and thewashing machine. Alternatively, arresters according to the inventioncould be installed inside the appliance, most preferably by themanufacturer of the appliance, near the appliance valve that may causethe pressure spike. During normal operation of a fluid or piping systemin which an arrester according to the invention has been installed,fluid (typically water) flows from first end fitting (e.g. 22 at theupstream or rearward end of arrester 10) toward the second end fitting.(e.g. 30 at the downstream or front end of arrester 10).

Arresters according to the invention preferably have a connectordisposed at each end for connecting the arrester to a pipe, hose, valve,or semi-rigid PEX riser. The end fittings described herein are onepreferred type of connector, particularly useful for a homeownerconnecting an arrester to a flexible water supply line. A length of pipeor hose attached to each end of an arrester according to the invention,or a valve attached to one end and another connector attached at theother end, may also be used as types of connectors. Different types ofconnectors may be used at each end of an arrester, depending on the useand type of installation for the arrester. Each end fitting describedherein preferably has a barbed end (e.g. barbed ends 24 and 32) tofacilitate insertion into a flexible hose. These barbed ends arepreferably widest near the neck portion (e.g. neck 21) and taper as theyextends outwardly from the neck, with the widest, barbed portion helpingto secure the barbed end within the hose and prevent the arrester fromdislodging from the flexible hose. A barbed end is not required, but ispreferred, particularly when arresters according to the invention areinstalled in flexible hoses. Other types of connectors, such as threadedconnectors or a clamp or crimp-type connector, or any other type ofconnector suitable for connection of the arrester to a pipe, hose,valve, or PEX riser (as will be understood by those of ordinary skill inthe art) may also be used. Such connectors would mate with similarconnectors installed on a flexible hose or tubing, piping, valve, or PEXriser with which an arrester according to the invention is to be used.Additionally, ribs or threads may optionally be provided around any neckportion of the arresters 10, 110, 210, 310, 510 or 610, similar to ribs423 and 433 in arrester 410, to aid in connection of the arrester to ahose or pipe. When used with hard piping, a threaded engagement betweenthe end fittings and the piping is preferred. Alternatively, the endfittings or other connectors could be soldered, cemented, damped, orotherwise secured to the piping or hose using any type of connectionsuitable for the materials used to manufacture the parts.

Arresters according to the invention may be connected at the site ofinstallation to, or pre-assembled with connections to, PVC or reinforcedPVC hose liners, EPDM and other single layer thermoplastic liners,polyethylene (LDPE, LLDPE, and HDPE) hose liners, including corrugatedhose liners made from these materials, UltraCore and other coextrudedhose liners, three layer and other multilayer extruded hose liners,silicone hose liners, flexible PEX hose liners, semi-rigid PEX risers,copper pipe, stainless steel pipe, or other metal piping. Arrestersaccording to the invention are useful with numerous commercial andhousehold appliances and fixtures, such as icemakers, washing machines,dishwashers, kitchen sinks, lavatory sinks, laundry sinks, toilets, andmini-bar sinks. Arresters according to the invention may also be usefulin industrial applications. When preassembled or pre-packaged alreadyconnected to a segment of hose or piping, barbed ends and neck portionson the end fittings may not be necessary and the hose or pipe may beattached to or integrally formed with part of the housing, body or endfittings of the arrester. Overmolded fittings, crimping, soldering,clamping, threaded engagement, ultrasonic welding, and other knownmethods may be used to integrate a hose or piping segment to thearresters according to the invention when the arrester is pre-assembledwith such a connection. Those of ordinary skill in the art willunderstand the modifications that would be needed for such alternateconnection configurations. The ends of such segment of hose or pipingmay come with threaded connectors that are easily attached at one end toa threaded connection at the water supply valve and attached at theother end to a threaded connection at the inlet of an appliance, such asa clothes washer, dishwasher, or ice maker.

The pressurized chambers (e.g. 20 and 120) in arresters according to theinvention preferably meet the latest edition of ASSE 1010 testingstandards to adequately reduce the impact of a pressure spike in thesystem. Although air is the preferred gas to use in the pressurizedchambers, other gases, preferably inert gases such as nitrogen, may alsobe used. Other materials, such as water, gel, or mechanical structures(such as springs), capable of absorbing the shock caused by the spikemay also be used with the pressurized chambers. A piston similar topiston 14 or piston 414 may be used with any arrester embodimentaccording to the invention. Other alterations and configurations ofpistons may also be used. These pistons are configured to move withinthe apparatus in response to a pressure spike between a resting positionand a forward position. The movement of the piston between the restingposition and the forward position is substantially in-line with thedirection of fluid flow through the fluid or piping system at a point ofupstream connection between the fluid or piping system and theapparatus. The movement from the forward position back to the restingposition is in the reverse direction, but is still substantially alongthe same axis as the direction of fluid flow through the fluid or pipingsystem at a point of upstream connection between the fluid or pipingsystem and the apparatus.

The materials described herein for manufacturing the various parts ofthe preferred embodiments of arresters according to the invention,including copper, copper allow, brass, metal sheet, stainless steel, andplastics, are not intended to be limiting. Any materials suitable towithstand the pressure in the system and in pressurized chamber, andsuitable for use with the particular type of fluid flowing through thesystem, may be used. With integrated parts, such as in arrester 410,arresters according to the invention may be made with as few as threeseparate components.

References to front (or forward) and rear (or back) herein generallyrefer to the direction of fluid flow through the piping system in whichan arrester according to the invention is installed, with forward beingin the downstream direction. Those of ordinary skill in the art willalso appreciate upon reading this specification and the description ofpreferred embodiments herein that modifications and alterations to theapparatus may be made within the scope of the invention and it isintended that the scope of the invention disclosed herein be limitedonly by the broadest interpretation of the appended claims to which theinventors are legally entitled.

We claim:
 1. A pressure spike reducing apparatus comprising: an outerhousing; an interior housing disposed within the outer housing, theinterior housing comprising a substantially cylindrical body having afirst diameter, the body having an annular shoulder at a first endforming an aperture with a second diameter smaller than the firstdiameter and the body having a second sealed end; a fluid channelpermitting the flow of fluid through the apparatus from an upstream endand out a downstream end, wherein at least a portion of the fluidchannel is disposed in an annular space between the outer housing andinterior housing; a piston disposed within the interior housing in afirst position when no pressure spike in the fluid channel is occurringand configured to temporarily move to a second position within theinterior housing in response to a pressure spike in the fluid channel;and a sealed pressurized chamber disposed within the interior housingbetween the piston and the sealed end, wherein the pressurized chamberhas an internal pressure that is only adjustable by movement of thepiston within the outer housing.
 2. The apparatus of claim 1 wherein thepiston comprises: a substantially cylindrical sidewall with an open enddisposed toward the annular shoulder of the interior housing body and aclosed end disposed toward the sealed end of the interior housing body;and a rounded shoulder between the sidewall and closed end.
 3. Theapparatus of claim 2 wherein the open end of the piston has a diameterslightly larger than that of the annular shoulder to retain the pistonwithin the interior housing.
 4. The apparatus of claim 2 wherein thepiston further comprises one or more annular protrusions or annularrecesses along the sidewall, each configured to receive a sealing ringdisposed between the piston and the interior housing.
 5. The apparatusof claim 1 wherein the outer housing comprises two separate bodies thatat least partially overlap and are sealed together.
 6. The apparatusaccording to claim 1 further comprising a first connector comprising asubstantially cylindrical neck disposed at an end of the apparatus and asecond connector comprising a substantially cylindrical neck disposed atanother end of the apparatus; and wherein each connector is configuredto selectively connect the apparatus to a pipe, flexible hose, valve, orsemi-rigid PEX riser to permit the flow of fluid through the fluidchannel.
 7. The apparatus of claim 6 wherein at least one of theconnectors is integrally formed with the outer housing.
 8. The apparatusof claim 6 wherein at least a portion of the neck of the connectordisposed at the end of the apparatus nearest the aperture in theinterior housing extends inwardly to abut a portion of the annularshoulder to block movement of the interior housing without substantiallyblocking the flow of fluid through the fluid channel.
 9. The apparatusof claim 8 wherein the interior housing further comprises at least onearm extending outwardly from the annular shoulder, the arm configured toengage with the portion of the neck extending inwardly.
 10. Theapparatus of claim 8 wherein the outer housing comprises at least onerib disposed on an interior surface of the outer housing near the sealedend of the interior housing body, the rib configured to block movementof the interior housing without substantially blocking the flow of fluidthrough the fluid channel
 11. The apparatus of claim 1 wherein the outerhousing comprises at least one rib disposed on an interior surface ofthe outer housing, the rib configured to block movement of the interiorhousing without substantially blocking the flow of fluid through thefluid channel.
 12. The apparatus of claim 11 wherein at least one rib isdisposed near the annular shoulder of the interior housing and whereinthe interior housing further comprises at least one arm extendingoutwardly from the annular shoulder, the arm configured to engage withthe rib.
 13. The apparatus of claim 6 wherein the interior housing isintegrally formed with one of the connectors.
 14. The apparatus of claim7 wherein the interior housing is also integrally formed with theconnector and outer housing.
 15. The apparatus of claim 5 wherein eachbody of the outer housing comprises a connector having an outwardlyextending substantially cylindrical neck configured to selectivelyconnect the apparatus to a pipe, flexible hose, valve, or semi-rigid PEXriser to permit the flow of fluid through the fluid channel.
 16. Theapparatus of claim 15 wherein the interior housing is integrally formedwith one of the bodies of the outer housing.
 17. The apparatus of claim15 wherein at least a portion of the neck of the connector disposed atthe end of the apparatus nearest the aperture in the interior housingextends inwardly to abut a portion of the annular shoulder to blockmovement of the interior housing without substantially blocking the flowof fluid through the fluid channel.
 18. The apparatus of claim 17wherein the interior housing further comprises at least one armextending outwardly from the annular shoulder, the arm configured toengage with the portion of the neck extending inwardly.